A tug of war is being waged over the size of the American home. Pulling in one direction are the forces of expansion: the well-financed dream for many of a sprawling single-family house. …Lining up on the other side are the powers of compression: shrinking family sizes; rising energy costs…. What is the net effect? The National Association of Home Builders reported that the median size of new family homes had dipped to 2,276 square feet and was expected to drop more in the coming months. …So for the first installment of a new column called “Living Small”… we visited the International Builders’ Show, to see how builders, manufacturers and architects are responding to this struggle. …The show revealed that to make the most of hobbled opportunities, developers, architects and builders are trimming the size of primary residences. Or dropping accessory dwelling units into backyards. Or investigating new technologies for  factory-built structures. [to access the full story, a NY Times subscription is required]